Exploring Graphs with igraph

g <- graph_from_data_frame(d = starwarsEL, 
                           directed = T, 
                           vertices = starwarsNL)
g

IGRAPH 0da289a DN-B 357 899 -- 
+ attr: name (v/c), type (v/c), type (e/c)
+ edges from 0da289a (vertex names):
 [1] Luke Skywalker       ->172 C-3PO                ->167
 [3] R2-D2                ->96  Darth Vader          ->202
 [5] Leia Organa          ->150 Owen Lars            ->178
 [7] Beru Whitesun lars   ->165 R5-D4                ->97 
 [9] Biggs Darklighter    ->183 Obi-Wan Kenobi       ->182
[11] Anakin Skywalker     ->188 Wilhuff Tarkin       ->180
[13] Chewbacca            ->228 Han Solo             ->180
[15] Greedo               ->173 Jabba Desilijic Tiure->175
+ ... omitted several edges

V(g)[name == "Luke Skywalker"]

+ 1/357 vertex, named, from 0da289a:
[1] Luke Skywalker

V(g)[type == 'a character']

+ 87/357 vertices, named, from 0da289a:
 [1] Luke Skywalker        C-3PO                 R2-D2                
 [4] Darth Vader           Leia Organa           Owen Lars            
 [7] Beru Whitesun lars    R5-D4                 Biggs Darklighter    
[10] Obi-Wan Kenobi        Anakin Skywalker      Wilhuff Tarkin       
[13] Chewbacca             Han Solo              Greedo               
[16] Jabba Desilijic Tiure Wedge Antilles        Jek Tono Porkins     
[19] Yoda                  Palpatine             Boba Fett            
[22] IG-88                 Bossk                 Lando Calrissian     
[25] Lobot                 Ackbar                Mon Mothma           
[28] Wicket Systri Warrick Nien Nunb             Qui-Gon Jinn         
+ ... omitted several vertices

E(g)[type == 'has films']

+ 173/899 edges from 0da289a (vertex names):
 [1] Luke Skywalker->Revenge of the Sith    
 [2] Luke Skywalker->Return of the Jedi     
 [3] Luke Skywalker->The Empire Strikes Back
 [4] Luke Skywalker->A New Hope             
 [5] Luke Skywalker->The Force Awakens      
 [6] C-3PO         ->Attack of the Clones   
 [7] C-3PO         ->The Phantom Menace     
 [8] C-3PO         ->Revenge of the Sith    
 [9] C-3PO         ->Return of the Jedi     
[10] C-3PO         ->The Empire Strikes Back
+ ... omitted several edges

E(g)['Luke Skywalker' %--% V(g)]

+ 18/899 edges from 0da289a (vertex names):
 [1] Luke Skywalker->172                    
 [2] Luke Skywalker->77                     
 [3] Luke Skywalker->blond                  
 [4] Luke Skywalker->fair                   
 [5] Luke Skywalker->blue                   
 [6] Luke Skywalker->19                     
 [7] Luke Skywalker->male                   
 [8] Luke Skywalker->Tatooine               
 [9] Luke Skywalker->Human                  
[10] Luke Skywalker->Revenge of the Sith    
+ ... omitted several edges

#Get rid of all edges NOT connected to LUKE SKYWALKER
g - E(g)[!'Luke Skywalker' %--% V(g)]

IGRAPH d839d1e DN-B 357 18 -- 
+ attr: name (v/c), type (v/c), type (e/c)
+ edges from d839d1e (vertex names):
 [1] Luke Skywalker->172                    
 [2] Luke Skywalker->77                     
 [3] Luke Skywalker->blond                  
 [4] Luke Skywalker->fair                   
 [5] Luke Skywalker->blue                   
 [6] Luke Skywalker->19                     
 [7] Luke Skywalker->male                   
 [8] Luke Skywalker->Tatooine               
+ ... omitted several edges

g %>%
  #get rid of all edges that DON'T have the type 'has films'
  {. - E(.)[type != 'has films']} %>%
  #get rid of all edges that are NOT connected FROM a SKYWALKER
  {. - E(.)[V(.)[!str_detect(name, 'Skywalker')] %->% V(.)]} %>%
  #get rid of all vertices that are NOT connected to other nodes
  #getting rid of the edges does not get rid of the nodes
  {. - V(.)[degree(.) == 0]}

IGRAPH 0fe62f7 DN-B 10 10 -- 
+ attr: name (v/c), type (v/c), type (e/c)
+ edges from 0fe62f7 (vertex names):
 [1] Luke Skywalker  ->Revenge of the Sith    
 [2] Luke Skywalker  ->Return of the Jedi     
 [3] Luke Skywalker  ->The Empire Strikes Back
 [4] Luke Skywalker  ->A New Hope             
 [5] Luke Skywalker  ->The Force Awakens      
 [6] Anakin Skywalker->Attack of the Clones   
 [7] Anakin Skywalker->The Phantom Menace     
 [8] Anakin Skywalker->Revenge of the Sith    
+ ... omitted several edges

movieCharProj <- g %>%
  {. - E(.)[type != 'has films']} %>%
  {. - V(.)[degree(.) == 0]} %>%
  #type has to be a boolean for projections to work
  {
    V(.)$type <- V(.)$type == 'a character'
    .
  } %>%
  bipartite_projection()

movieCharProj

$proj1
IGRAPH 6c12ee7 UNW- 7 21 -- 
+ attr: name (v/c), weight (e/n)
+ edges from 6c12ee7 (vertex names):
 [1] Revenge of the Sith--Return of the Jedi     
 [2] Revenge of the Sith--The Empire Strikes Back
 [3] Revenge of the Sith--A New Hope             
 [4] Revenge of the Sith--The Force Awakens      
 [5] Revenge of the Sith--Attack of the Clones   
 [6] Revenge of the Sith--The Phantom Menace     
 [7] Return of the Jedi --The Empire Strikes Back
 [8] Return of the Jedi --A New Hope             
+ ... omitted several edges

$proj2
IGRAPH 9f0f615 UNW- 87 1793 -- 
+ attr: name (v/c), weight (e/n)
+ edges from 9f0f615 (vertex names):
 [1] Luke Skywalker--C-3PO              Luke Skywalker--R2-D2             
 [3] Luke Skywalker--Darth Vader        Luke Skywalker--Leia Organa       
 [5] Luke Skywalker--Owen Lars          Luke Skywalker--Beru Whitesun lars
 [7] Luke Skywalker--Obi-Wan Kenobi     Luke Skywalker--Anakin Skywalker  
 [9] Luke Skywalker--Wilhuff Tarkin     Luke Skywalker--Chewbacca         
[11] Luke Skywalker--Yoda               Luke Skywalker--Palpatine         
[13] Luke Skywalker--Nute Gunray        Luke Skywalker--Ayla Secura       
[15] Luke Skywalker--Mace Windu         Luke Skywalker--Ki-Adi-Mundi      
+ ... omitted several edges

movieCharProj[[2]] %>%
  {E(.)$weight} %>%
  summary

   Min. 1st Qu.  Median    Mean 3rd Qu.    Max. 
   1.00    1.00    1.00    1.35    1.00    6.00 

movieCharProj[[2]] %>%
  {. - E(.)[weight < 3]} %>%
  {. - V(.)[degree(.) == 0]}

IGRAPH dedc1cd UNW- 23 134 -- 
+ attr: name (v/c), weight (e/n)
+ edges from dedc1cd (vertex names):
 [1] Luke Skywalker--C-3PO              Luke Skywalker--R2-D2             
 [3] Luke Skywalker--Darth Vader        Luke Skywalker--Leia Organa       
 [5] Luke Skywalker--Obi-Wan Kenobi     Luke Skywalker--Chewbacca         
 [7] Luke Skywalker--Yoda               Luke Skywalker--Palpatine         
 [9] Luke Skywalker--Han Solo           Luke Skywalker--Wedge Antilles    
[11] C-3PO         --R2-D2              C-3PO         --Darth Vader       
[13] C-3PO         --Leia Organa        C-3PO         --Owen Lars         
[15] C-3PO         --Beru Whitesun lars C-3PO         --Obi-Wan Kenobi    
+ ... omitted several edges

anakinIsLukesFather <- g %>%
  as_data_frame('both') %>%
  {
    .[[1]] <- .[[1]] %>% filter(name != 'Darth Vader')
    .[[2]] <- .[[2]] %>% mutate(from = sapply(from, function(x){ifelse(x == 'Darth Vader', 'Anakin Skywalker', x)})) %>% distinct
    .
  } %>%
  {graph_from_data_frame(.[[2]], T, .[[1]])} %>%
  {. - E(.)[type != 'has films']} %>%
  {. - V(.)[degree(.) == 0]} %>%
  {
    V(.)$type <- V(.)$type == 'a character'
    .
  } %>%
  bipartite_projection() %>%
  .[[2]] %>%
  {. - E(.)[weight < 3]} %>%
  {. - V(.)[degree(.) == 0]}